Method and apparatus for efficiently controlling access for system load adjustment in mobile communication systems

ABSTRACT

The present invention relates to a method and apparatus for efficiently controlling access for system load adjustment in mobile communication systems. In a wireless communication system according to one embodiment, the method for transmitting and receiving data by a terminal including a user equipment (UE) non access stratum (NAS) and a UE access stratum (AS) includes the steps of: receiving by the UE AE, information including emergency call-related information which includes barring information by type for the emergency call, from a base station; transmitting, by the UE NAS, a service request for the emergency call to the UE AS; and determining, by the UE AS, whether to bar the service request on the basis of emergency call-related information. According to one embodiment, during the emergency call transmission, network congestion can be easily controlled by enabling various types of emergency calls to be transmitted, and enabling access to be barred information according to the situation of a communication network and types of emergency calls. Also, even when a specific type of emergency call is barred from access, the terminal can change to another type of emergency call and try for access. Therefore, it is effective in that an emergency call can be transmitted in various schemes even in a state where the network is congested.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/375,119 filed Jul. 28, 2014, which is a 371 of InternationalPatent Application No. PCT/KR2013/000667 filed on Jan. 28, 2013, whichclaims priority to U.S. Provisional Patent Application No. 61/591,385filed on Jan. 27, 2012, and U.S. Provisional Patent Application No.61/595,646 filed on Feb. 6, 2012, the disclosures of which are hereinincorporated by reference in their entirety.

BACKGROUND 1. Field

The present invention relates to a method and apparatus of controllingnetwork access efficiently to adjust the load of a mobile communicationsystem.

2. Description of Related Art

Mobile communication systems were developed to provide mobile users withcommunication services. With the rapid advance of technologies, themobile communication systems have evolved to the level capable ofproviding high speed data communication service beyond the earlyvoice-oriented services.

Recently, the next generation mobile communication system moves itsfocus to Human to Machine (H2M) and Machine to Machine (M2M)communication beyond Human to Human (H2H) communication. In order tomeet such a requirement, the 3^(Rd) Generation Partnership Project(3GPP) communication standard organization is standardizing on MachineType Communications (MTC). MTC has characteristics different from thoseof the conventional radio communication. The MTC characteristics areclassified variously depending on the usage purpose. For example, theMTC devices requiring communication a few times a day withoutperiodicity have delay tolerant characteristic. In contrast, the MTCdevice fixed at a location to collect and transfer predeterminedinformation has the characteristic of low mobility. The mobile networkoperator has to provide services in consideration of the coexistence ofthe MTC devices having various characteristics and legacy terminals.

Typically, a plurality of MTC devices exists within a cell. If the MTCdevices attempt access simultaneously, the load of the access networkmay increase abruptly. This makes the network unstable and, as aconsequence, most of the terminals are likely to fail initial access.Since the most MTC devices have delay tolerant characteristic, it is notnecessary to establish connection to the base station immediately. Ifthe load of the radio network exceeds a predetermined threshold value,the base station may restrict the initial attach of the MTC devicesfirst to control the radio network load. The 3GPP working groups arediscussing adoption of an extended access baring technique to controlthe radio access network lode. The normal access barring techniqueinformation is carried in a System Information Block (SIB).

The present invention proposes an access barring technique capable ofcontrolling aforementioned various service accesses, particularlyemergency call and MTC accesses.

The present invention aims to provide a method and apparatus forexecuting access barring under various conditions depending on the typeof the emergency call and allowing a terminal to attempt emergency callin various manners in an environment supporting various types ofemergency calls.

Also, the present invention aims to provide a method and apparatus forallowing an MTC device to transmit EAB information associated withvarious operators in the form of an EAB set.

SUMMARY

In accordance with an aspect of the present invention, a datacommunication method of a terminal including a User Equipment (UE)Non-Access Stratum (NAS) and a UE Access Stratum (AS) in a wirelesscommunication system includes receiving, at the UE AS, emergency callinformation including barring information per emergency call type from abase station, transmitting, at the UE NAS, an emergency call servicerequest to the UE AS, and determining, at the UE AS, whether to bar theservice request based on the emergency call information.

In accordance with another aspect of the present invention, a datacommunication method of a base station in a wireless communicationsystem includes transmitting a message including data schedulinginformation to a terminal and transmitting emergency call informationincluding barring information per emergency call type according to thedata scheduling information.

In accordance with another aspect of the present invention, a terminalfor communicating data in a wireless communication system includes aUser Equipment (UE) Access Stratum (AS) which receives informationincluding emergency call information including barring information peremergency call type from a base station and a UE Non-Access Stratum(NAS) which transmits an emergency call service request to the UE AS,wherein the UE AS determine whether to bar the service request based onthe emergency call information.

In accordance with another aspect of the present invention, a basestation for communicating data in a wireless communication systemincludes a transceiver which transmits a message including datascheduling information to a terminal and a controller which controlstransmitting emergency call information including barring informationper emergency call type according to the data scheduling information.

In accordance with another aspect of the present invention, a datacommunication method of a base station in a wireless communicationsystem includes transmitting a Public Land Mobile Network (PLMN) listsupported by the base station to a terminal and transmitting a messageincluding barring information per PLMN to the terminal, wherein theper-PLMN barring informations correspond in position to PLMNs containedin the PLMN list.

In accordance with still another aspect of the present invention, a datacommunication method of a terminal in a wireless communication systemincludes receiving a list of Public Land Mobile networks (PLMNs)supported by a base station from the base station and receiving amessage including per-PLMN barring information from the base station,wherein the per-PLMN barring informations included in the messagecorrespond in position to PLMNs contained in the PLMN list.

The method and apparatus of the present invention is advantageous interms of facilitating network congestion control by making in possibleto transmit various types of emergency calls and applying access barringdepending on the network situation and type of the emergency call. Also,the method and apparatus of the present invention is advantageous interms of diversifying emergency call transfer schemes in a networkcongestion situation by making it possible to change an access-barredemergency call type for another type of emergency call.

Also, the method and apparatus of the present invention is advantageousin terms of reducing system load and overhead by diminishing the size ofthe message in such a way of determining the message format per operatorbased on the EAB information of the MTC device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an ACB technique in the conventionalLTE system;

FIG. 2 is a diagram for explaining the modification period;

FIG. 3 is a signal flow diagram illustrating the normal SIB transmissionmethod;

FIG. 4 is a flowchart illustrating the ACB procedure of emergency callin the conventional method;

FIG. 5 is a diagram for explaining the procedure of controlling ACB of aplurality of emergency calls in the present invention;

FIG. 6 is a signal flow diagram illustrating the operation procedure ofembodiment 1;

FIG. 7 is a flowchart illustrating the ACB parameter selection procedurewhen the UE AS performs the barring check;

FIG. 8 is a flowchart illustrating the UE AS operation in embodiment 1;

FIG. 9 is a flowchart illustrating the UE NAS operation in embodiment 1;

FIG. 10 is a signal flow diagram illustrating the EAB informationacquisition procedure;

FIG. 11 is a diagram illustrating configurations of EAB informationincluded in SIB14;

FIG. 12 is a signal flow diagram illustrating a procedure of providingmultiple EABs in the system overload situation;

FIG. 13 is a flowchart illustrating the eNB operation;

FIG. 14 is a block diagram illustrating a configuration of the UEaccording to an embodiment of the present invention;

FIG. 15 is a block diagram illustrating a configuration of the eNBaccording to an embodiment of the present invention;

FIG. 16 illustrates an example of operations of a first UE according tocertain embodiments of this disclosure;

FIG. 17 illustrates an example of operations of a second UE according tocertain embodiments of this disclosure; and

FIG. 18 illustrates an example of operations of a UE according tocertain embodiments of this disclosure.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention are described withreference to the accompanying drawings in detail.

Detailed description of well-known functions and structures incorporatedherein may be omitted to avoid obscuring the subject matter of thepresent invention. This aims to omit unnecessary description so as tomake the subject matter of the present invention clear.

Advantages and features of the present invention and methods ofaccomplishing the same may be understood more readily by reference tothe following detailed description of exemplary embodiments and theaccompanying drawings. The present invention may, however, be embodiedin many different forms and should not be construed as being limited tothe exemplary embodiments set forth herein. Rather, these exemplaryembodiments are provided so that this disclosure will be thorough andcomplete and will fully convey the concept of the invention to thoseskilled in the art, and the present invention will only be defined bythe appended claims. Like reference numerals refer to like elementsthroughout the specification.

The present invention relates to a method and apparatus for controllingaccess efficiently to adjust the system load in a mobile communicationsystem. The present invention proposes an access baring method relatedto emergency call and MTC access.

In an embodiment, UE AS and UE NAS may be logical components included inthe User Equipment (UE). Depending on the implementation, the logicalcomponents may be configured as hardware modules.

Prior to starting explanation of the present invention, the Access ClassBarring (ACB) technique of the convention LTE system is described.

FIG. 1 is a diagram illustrating an ACB technique in the conventionalLTE system. The ACB is a technique for controlling UE access to controlsystem load and implemented in such a way that the eNB provides the UEswith the barring information through broadcasting in advance and thusthe UEs attempts access to the network based on the their classes andthe barring information broadcast by the eNB 100. If new ACB istriggered at step 115, the eNB 100 may notify the UE AS 105 that theSystem Information Block (SIB) is to be modified soon for the new ACBusing systemInfoModification IE of the paging message at step 120.

If the paging message is received, the UE is aware at step 130 that theSIB is to be modified soon. The systemInfoModification IE included inthe paging message is an indicator indicating the modification of SIB,the indicator being provided in various forms depending on theembodiment.

The eNB 100 notifies the UEs that SIB is to be modified soon, using thepaging message transmitted during the modification period 125 beforebroadcasting the modified SIB. Afterward, the modified SIB is broadcastduring the next modification period. The modification period isdescribed in detail later.

After the modification period ends with the receipt of the pagingmessage, the UE receives SIB1 135 carrying new information.

There are various types of SIBs for different purposes. The LTE Rel-11standard specifies SIB1 to SIB14 and it is to diversify the SIBs forsupporting new functions. Among the SIBs, SIB1 may include thescheduling information of other SIBs.

Accordingly, the SIB1 has to be received first in order to receive otherSIBs. After the receipt of the SIB1, the UE receives SIB2 including ACBinformation. The UE AS 105 stores the ACB information at step 145. If aservice, i.e. communication service, is required, the UE NAS 110requests the UE AS 105 for the service at step 150. The UE AS 105determines whether to accept the access based on the store ACBinformation at step 155. The UE is allocated one of the classes 0 to 9inevitably. The UE may be allocated one of classes 11 to 15 for specialpurposes additionally. Among the classes, class 10 relates to theemergency call. The eNB 100 may restrict the access of a certain class.In the LTE standard, it is impossible to designate one of classes 0 to 9for access barring but it is possible to designate at least one of thespecial purpose classes 11 to 15 for special purposes for accessbarring.

Meanwhile, the eNB 100 provides the barring factors and barring timeinformation associated with classes 0 to 9. The UE selects one of 0 and1 randomly and compares the selected value with the barring factor. Ifthe value selected by the UE is equal to or less than the barringfactor, this means that the access is allowed. If the value selected bythe UE is greater than the barring factor, this means that the eNB 100bars the access and thus the eNB 100 notifies the UE NAS 110 of thereject of the access at step 160. If the access is rejected, the UE AS105 calculates Tbarring value 165 based on the barring time informationusing equation (1). Equation 1 is a formula for calculating the Tbarringvalue 165 according to an embodiment. Depending on the embodiment, theTbarring value 165 may be calculated differently.“Tbarring”=(0.7+0.6*rand)*ac-BarringTime  (1)

After the Tbarring time elapses, the UE AS 150 notifies the UE NAS 110that it is possible to attempt access again at step 170.

At this time, the UE NAS 110 instructs to retry access to the UE AS 105at step 175, and the UE AS 105 performs barring check again at step 180.The procedure may correspond to a normal Mobile Originating (MO) call orsignaling, i.e. service request triggered by the UE.

The emergency call triggered by the UE differs somewhat from the normalMO call in procedure. The ACB information of the emergency call differsfrom the MO call or signaling. That is, the barring factor or barringtime information is replaced with ac-barringForEmergency information.This IE is of the Boolean form indicating only whether the emergencycall is allowed. If the IE is set to TRUE, this indicates the emergencycall is not allowed and thus, after checking predetermined additionalconditions, the access is rejected finally. Since no barring timeinformation is provided, the UE AS 105 does not notify the UE NAS 110 ofaccessibility after Tbarring. The ACB operation for emergency call isdescribed in more detail with reference to FIG. 4.

In the ACB operation for an MTC device, the ACB operation described withreference to FIG. 1 is not applied in order to provide the MTC devicewith the ACB information as quick as possible. Also, they differ fromeach other in ACB information format made up of the barring factor andbarring time. The ACB operation for the MTC device is made in moredetail later. For reference, the ACB for the purpose of MTC is referredto as Extended Access Barring (EAB) distinguished from the legacy ACB inthe LTE standard.

FIG. 2 is a diagram for explaining the modification period.

Referring to FIG. 2, the normal SIB is performed with the concept ofmodification period 210. That is, the evolved Node B (eNB) notifies theUE before SI update that the SI 200 is to be updated using the pagingmessage during the modification period. If the paging message includessystemInfoModification IE, this means that the updated SIB 205 istransmitted during the next medication period.

Even when just one of the SIBs is modified, this is informed in thepaging message. In the case of SIB10 and SIB11 carrying ETWSinformation, however, the SIB is updated independently of the boundaryof the modification period. If the paging message includes theetws-Indication IE indicating existence of ETWS information, the UEreceives SIB10 and SIB11 immediately. The length of the modificationperiod is notified by SIB2, and tis maximum value is 10.24 seconds. Thismeans that it may take up to 10.24 seconds to deliver the ACBinformation. Accordingly, it is not preferred to apply the modificationperiod to the MTC device to which the ACB information has to bedelivered promptly.

FIG. 3 is a signal flow diagram illustrating the normal SIB transmissionmethod.

Referring to FIG. 3, the eNB 305 may detects abrupt increase of radionetwork load at step 315.

The eNB 305 restricts the initial attach attempts of the UEs 300 tocontrol the radio network load at step 320.

In order to accomplish this, the eNB 305 sends the UE 300 the pagingmessage including SystemInfoModification IE at step 325.

The UE 300 receives the paging message and checks that the SIB ismodified in the next modification period at step 330.

If the next modification period 340 arrives, the UE 300 may attemptdecoding SIB1 at step 345. This is because the SIB1 includes schedulinginformation on other SIBs.

The UE 300 may receive the SIB2 including EAB information at step 350.The UE 300 may acquire the modified ACB information from the SIB2 atstep 355.

FIG. 4 is a flowchart illustrating the ACB procedure of emergency callin the conventional method.

Referring to FIG. 4, the UE AS receives the SIB2 broadcast by the eNB atstep 400. The SIB2 may include an ac-BarringInfo IE carrying the barringinformation.

The UE AS determines whether there is an emergency call request form theUE NAS at step 405.

If an emergency call is triggered, the UE AS determines whether theac-BarringForEmergency IE included in the ac-BarringInfo IE is set toTRUE at step 410. If it is set to a value other than TRUE, the UE ASregards that the call is accepted. Otherwise if it is set to TRUE, theUE AS determines whether at least one of the special purpose classes 11to 15 is included at step 415.

If not special purpose class is included, the UE AS regards that thecall is not allowed at step 435 and notifies the UE NAS of this at step440. If at least one special purpose class is included, the UE AS checksthe barring information on the classes 11 to 15 which is included in theac-BarringInfo IE. In an embodiment, 5-bit bitmap indicating the barringstate of the special purpose classes is included in the ac-BarringInfoIE. The ac-BarringForMO-Data IE of the ac-Barring Info IE includes a5-bit ac-BarringForSpecialAC IE. In an embodiment, the individual bitsmay be mapped to the ACs 11 to 15 sequentially. If each bit is set to 1,it is regarded that the corresponding AC is barred. At this time, theACs 12, 13, and 14 are available in the home country while the ACs 11and 15 are available only in HPLMN/HEPLMN. If at least one of thespecial purpose classes is allowed, it is regarded that the call accessis accepted at step 430. Afterward, the UE may perform random access forconnection to the eNB.

As the services available for provision are diversified, the CallAdmission Control (CAC) for controlling the system load becomescomplicated. Particularly, the emergency call is allocated a priorityhigher than the normal access for access allowance. However, theemergency call also may be sorted into one of various types such as SMS,voice, and video of which influences to the system load differ from eachother. Accordingly, it is necessary to perform CAC in consideration ofthe type of emergency call. In the conventional technology, there isonly one type of the emergency call. However, as the services providedthrough the mobile communication system become diversified, it has to beconsidered to sort the emergency calls into various types. For example,the emergency calls may be sorted into Short Message Service (SMS) type,voice type, and video type. The influences to the system load may differdepending on the type of emergency call. For example, the SMS type maycarry restricted information but have relatively small influence to thesystem load. The video type may carry enriched information but haverelatively large influence to the system load. Accordingly, it isnecessary for the UE NAS to select the type of emergency call accordingto the system environment and, if the barring information is provided inadaptation to the type of the emergency call, it is possible to managethe emergency calls more efficiently in view of system load. Embodiment1 proposes a UE operation for providing the barring informationsadaptive to the types of emergency calls and utilizing the type-adaptivebarring information efficiently.

The second embodiment proposes a method of providing the ACB informationto the MTC device. Particularly, the second embodiment proposes a methodof configuring the ACB information.

Embodiment 1

Embodiment 1 proposes a UE operation for providing the barringinformations adaptive to the types of emergency calls and utilizing thetype-adaptive barring information efficiently. In the present invention,plural types of emergency calls are defined with respective ACBinformations. The UE determines the types of the emergency calls basedon the ACB information broadcast by the eNB.

FIG. 5 is a diagram for explaining the procedure of controlling ACB of aplurality of emergency calls in the present invention.

In FIG. 5, the UE AS 505 and the UE NAS 510 may be logical or physicalmodules included in the UE.

Referring to FIG. 5, if new ACB is triggered at step 515, the eNB 500notifies the UE AS 505 that the SIB is to be changed soon due to the newACB, using the systemInfoModification IE of the paging message at step520.

Upon receipt of the paging message, the UE is aware at step 530 that theSIB is modified soon. The eNB notifies the UEs that the SIB is modifiedsoon, using the paging message transmitted during the modificationperiod 525 before broadcasting the modified SIB.

Afterward, the modified SIB is broadcast in the next modificationperiod. After receiving the paging message in the modification period,the UE receives the SIB1 at step 535 to acquire new SIB.

At step 540, the UE receives SIB2 including ACB information based on theSIB1 received at step 535. The ACB information may include the barringinformation determined depending on the type of emergency call. In anembodiment, the emergency calls are sorted into SMS type, voice type,and video type. Each type has ac-BarringForEmergency IE indicatingwhether its access is allowed. Depending on the embodiment, the ACBinformation may include barring factor and barring time per type ofemergency call.

The UE AS 505 stores the ACB information at step 545. In the presentinvention, the ACB information may be sent to the UE NAS 510. The ACBinformation may be transferred to the UE NAS 510 as it has been receivedby the UE AS 505 or after being processed. For example, the informationto be transferred to the UE NAS 510 may be per-emergency call type ACBinformations, per-emergency call type access allowance probabilityvalues as virtual ACB check result, or restricted emergency call typelist information. The information format may be selected when the UE NAS510 triggers the emergency call. In an exemplary case of high systemload, the voice or video type emergency call may cause significantburden to the system. Accordingly, the eNB may allow for only the SMStype access but not two other types.

The UE NAS 510 selects an appropriate type and sends the UE AS 505 anemergency call service request at step 550. If the UE NAS 510 hasreceived the parameters included in the SIM at step 545, step 550 may beperformed selectively.

The UE AS 505 performs barring check at step 555. The UE AS 505 performsthe barring check finally. Since the ACB information has be transferredto the UE NAS 510 at step 545, the barring probability of the request islikely to decreases after the UE AS 505 has perform the barring check.However, if the ACB information is corrupted due to any reception erroror if the emergency call type is selected without ACB information, thismay cause barring the call. If the call is not allowed, the UE AS 505notifies the UE NAS 510 of this at step 560.

The UE NAS 510 selects another type of emergency call to retry at step570.

The UE AS 505 performs barring check at step 565. If it is determinedthat the call is allowed, the UE AS 505 attempts random access to theeNB 500.

In FIG. 5, the UE AS 505 sends the UE NAS 510 the received barringinformation, and the UE NAS 510 select an appropriate type of emergencycall based on the barring information and sends the UE AS 505 a servicerequest. At this time, the UE AS 505 performs the final barring check onthe request. In the present invention, however, other processes may beperformed. The process of transferring the barring information receivedat the UE AS 505 to the UE NAS 510 is identical with the process in FIG.5. However, the UE NAS 510 may perform the barring check as well asselect the appropriate type of emergency call. In this case, the servicerequest transmitted from the UE NAS 510 to the UE AS 505 is transmittedto the eNB 500 immediately without barring check of the UE AS 505.Although the two aforementioned methods are similar to each other withthe exception whether the barring check is performed by the UE NAS 510or the UE AS 505. In another method, the UE AS 505 sends the UE NAS 510the information on whether the service request of the UE NAS 510 isbarred other than the barring information like the conventional ACB. TheUE NAS 510 reselects another type in the stead of the barred emergencycall type to retry the service request.

FIG. 6 is a signal flow diagram illustrating the operation procedure ofembodiment 1.

In FIG. 6, the UE NAS 600 and UE AS 650 may be physical or logicalcomponents includes in the UE.

The eNB 610 sends the UE AS 605 the SIB2 at step 615. The SIB2 includesthe ACB information, i.e. ac-BarringInfo IE. The ac-Barring Info IEincludes ac-BarringForEmergency, ac-BarringForMO-Signaling, andac-BarringForMo-Data IE. The IEs include the conventional emergency callbarring information, Mobile originating-signaling barring information,and mobile originating data barring information, respectively. In anembodiment, the ac-BarringInfo IE may include new barring informationson various types of emergency calls in addition to theconventionally-included informations. For example, the ac-BarringInfo IEfurther includes ac-BarringForEmergency-SMS,ac-BarringForEmergency-Voice, and ac-BarringForEmergency-Video IEs.These new IEs have Boolean values indicating whether the respectiveemergency call types are access-barred.

The UE AS 650 sends the UE NAS 600 the ac-BarringInfo IE at step 620.Step 620 is optional and thus the ac-BarringInfo IE may not betransmitted. If the ac-BarringInfo IE is received, the ac-BarringInfo IEmay facilitate for the UE NAS 600 to select an appropriate type ofemergency call.

The UE NAS 600 triggers an emergency call at step 625.

The UE NAS 600 selects an emergency call type at step 630 and sends theUE AS 650 a service request at step 635.

The UE AS 650 performs barring check at step 640. If the ACB informationhas been transferred to the UE NAS and if the UE NAS 600 has selected anappropriate type of emergency call based on the ACB information, thisstep is obviated. In an embodiment, however, it is not ruled out thatthe ACB information is not sent to the UE NAS 600 and thus this step isincluded.

If the access for the call is allowed, the UE AS 605 attempts access tothe eNB at step 645. Otherwise if the access for the call is notallowed, the UE AS 650 notifies the UE NAS 600 of the access failure.

The UE NAS 600 selects another type of emergency call at step 655 andsends the UE AS 605 a service request at step 660. The service requestmay be made based on the signal received at step 650 depending on theembodiment.

FIG. 7 is a flowchart illustrating the ACB parameter selection procedurewhen the UE AS performs the barring check.

Referring to FIG. 7, the UE AS determines whether the corresponding UEis a legacy UE at step 700. In the present invention, the term ‘legacyUE’ means the UE which cannot support multiple emergency calls andrelated UE operations. That is, the legacy UE can recognize only asingle type of emergency call. If the UE is the legacy UE, the UE cannotdistinguish among the ACB informations but recognize all as the legacyACB information and thus determines whether the access is allowed inconsideration of only the legacy ACB information as the operation atstep 705.

If the UE is not a legacy UE, the UE NAS checks the types of theemergency call at steps 710, 720, and 730, and determines whether theaccess is allowed at steps 715, 725, and 735 based on the correspondingACB information.

FIGS. 8 and 9 are directed to the case where a legacy UE exists in theservice area of the eNB supporting multiple emergency call types. It isalso possible that the eNB is a legacy eNB which does not supportmultiple emergency call types although the UE support the multipleemergency call types. It is also possible to define the UE operations insuch cases, which are described in detail with reference to FIGS. 16,17, and 18.

FIG. 8 is a flowchart illustrating the UE AS operation in embodiment 1.

Referring to FIG. 8, the UE AS receives ac-BarringInfo IE in the SIB2broadcast by the eNB at step 800.

The UE determines whether the UE itself is the legacy UE at step 805.The legacy UE which cannot understand the ACB information proposed inthe present invention performs the legacy ACB operation at step 815.

In the case of non-legacy UE, the UE AS sends the UE NAS theac-BarringInfo IE at step 810.

The UE AS determines whether an emergency call is triggered by the UENAS at step 820.

If so, the UE AS checks the type of the emergency call and applies theACB information corresponding thereto at step 825.

The UE AS checks the applied ACB information and determines whether thecorresponding type call access is allowed at step 830. That is, if theac-BarringForEmergency IE is not set to TRUE, the UE AS regards that theaccess is allowed for the corresponding call. Otherwise if the IE is setto TRUE, the UE determines whether the IE includes at least one of thespecial purpose classes 11 to 15 in addition to the classes 0 to 9 atstep 835.

If there is not special class included, the UE AS regards that the callis not allowed and notifies the UE NAS of this. If at least one specialpurpose class is included, the UE AS checks the barring informations onthe classes 11 to 15 included in the ac-BarringInfo IE at step 845. Thebarring indication informations on the special purpose classes 11 to 15are included in the ac-BarringInfo IE in the form of 5-bit bitmap.

If the at least one of the special purpose classes of the UE is allowedfor access, the UE AS regards that the access for the call is allowed atstep 850. Afterward, the UE may perform a random access procedure to tryto attach to the eNB.

FIG. 9 is a flowchart illustrating the UE NAS operation in embodiment 1.

Referring to FIG. 9, the UE NAS determines whether an emergency call isrequested at step 900.

If an emergency call is requested, the UE NAS determines whether the UEis a legacy UE at step 905.

If the UE is a legacy UE, the UE NAS performs legacy ACB operation atstep 945.

If the UE is not a legacy UE, the UE NAS performs one of two processesselectively.

The first process is of selecting the type of emergency call withoutchecking the ACB information at step 910.

After selecting the emergency call type, the UE NAS sends the UE AS aservice request for the emergency call at step 915.

The UE NAS determines whether a request failure is reported by the UE ASat step 920.

If the access reject is reported by the UE AS, the UE NAS selectsanother type of emergency call and returns the procedure to step 915.Typically, the emergency call type reselection may be performedaccording to a predetermined rule. For example, the video type emergencycall has failed for the first service request, the SMS or voice typeemergency call may be selected for low system load. This is because theSMS or vice type emergency call causing low system load as compared tothe vide type emergency call has relatively high probability for access.From the view point of the eNB, it may allow for the access causing nosignificant system load such as SMS type rather the barring all thetypes of emergency call accesses even in the high system load situation.Unlike the conventional technology, if the UE AS provides the UE NAS thereceived ACB information, the UE NAS may select the access-allowedemergency call type. That is, the UE NAS determines whether theac-BarringInfo has been received from the UE AS in advance at step 930.

The UE NAS selects an emergency call type based on the information atstep 935. The UE NAS sends the UE AS the service request for the call atstep 940. Although the UE NAS has the ACB information, an error mayoccur in receiving signals. Accordingly, the UE AS may perform thebarring check before attempt real access to the eNB. In this case, theUE NAS waits for the barring check result from the UE AS at step 920. Ifit fails, the UE NAS selects another type to retry.

FIGS. 16, 17, and 18 are flowchart illustrating the operations of the UEsupporting enhanced multiple emergency call types in connection with thelegacy eNB. According to this embodiment, three UE operations areproposed. In this embodiment, the UE may include the UE AS and UE NAS.

The first UE operation is described with reference to FIG. 16. Referringto FIG. 16, the UE receives SIB2 broadcast by the serving eNB at step1600. The system information includes the barring information.

The UE determines whether the SIB2 includes the barring informationproposed in the present invention at step 1605. If the SIB2 does notinclude the barring information proposed in the present invention, theeNB is the legacy eNB which does not support multiple emergency calltypes. If the SIB2 includes the barring information, the UE performs theabove-described UE operation at step 1610. If the eNB is the legacy eNB,the UE applies the ACB information on the legacy emergency call to thevoice type emergency call at step 1615. As described above, the legacyACB information, i.e. ac-BarringForEmergency IE, is sent to the UE inSIB2 too.

If it is necessary to request for an emergency call, the UE triggers thevoice type emergency call only and performs the barring check incompliance with the legacy ACB operation at step 1620.

The second UE operation is described with reference to FIG. 17.Referring to FIG. 17, the UE receives the SIB2 broadcast by the servingeNB at step 1700. The system information includes the barringinformation.

The UE determines whether the SIB2 includes the barring informationproposed in the present invention at step 1705. If the barringinformation is included, the UE perform the above-described operation atstep 1710.

If the eNB is a legacy eNB, the UE applies the ACB information on thelegacy emergency call to all the types of emergency calls at step 1715.

If it is necessary to request for an emergency call, the UE triggers oneof the various types of emergency calls and performs the barring checkin compliance with the legacy ACB operation at step 1720.

The last UE operation is described with reference to FIG. 18. Referringto FIG. 18, the UE receives the SIB2 broadcast by the serving eNB atstep 1800. The system information includes the barring information. TheUE determines whether the SIB2 includes the barring information proposedin the present invention at step 1805. If the barring information isincluded, the UE performs the above-described operation at step 1810.

If the eNB is a legacy eNB, the UE performs scaling on the ACBinformation of the legacy emergency call and applies the scaled ACBinformation to the respective types of emergency calls at step 1815.Here, scaling means modifying the legacy ACB information according to apredetermined rule. For example, if the legacy ACB information allowsfor the legacy emergency call access, it is regarded that the SMS andvoice type emergency calls are allowed for access with the exception ofthe video type emergency call. Such a scaling-based method is used toallow for only the emergency call type causing influence equal to orless than that which the legacy emergency call access causes to theradio network.

If it is necessary to request for an emergency call, the UE triggers oneof the various types of emergency calls and performs the barring checkbased on the scaled ACB information at step 1820.

Embodiment 2

Embodiment 2 proposes a method for providing ACB information to the MTCdevice. Hereinafter, the ACB information for MTC device is referred toas EAB information. The MTC device communication service isdelay-tolerant and thus assigned a priority lower than that of thenormal UE communication service. Accordingly, in the situation where thenetwork load increases, the access barring may be applied to the MTCdevice communication service first as compared to the normal UEcommunication service.

The EAB information is not applicable to the normal UE but MTC device.As described with reference to FIG. 2, it is not preferred to apply themodification period to the MTC device to which the EAB information hasto be delivered promptly. Accordingly, The MTC device performs adistinguished operation to receive SIB14 carrying EAB information. Priorto starting explanation of the embodiment, a procedure of receivingSIB14 is described.

FIG. 10 is a signal flow diagram illustrating the EAB informationacquisition procedure.

Although the description is directed to the MTC device, the presentinvention is not limited thereto but may be embodied by applying all thetypes of UEs having communication capability.

Referring to FIG. 10, if it is determined to control the initial attachof the MTC device 1005 due to the increase of the radio network load,the eNB 1010 sends the UE 1005 the paging message including aneab-indication IE at step 1015. According to an embodiment, theeab-indication IE is used to notify the UE 1005 of the modification ofEAB information.

If the eab-indication is received, the UE 1005 retards the access atstep 1020 until new EAB information is received. In order to acquire newEAB information, the UE 1005 receives SIB1 from the eNB 1010 at step1025. The SIB1 may include SIB scheduling information.

The UE 1005 receives SIB14 include the EAB information based on thescheduling information at step 1030.

The UE 1005 may apply the newly acquired EAB information at step 1035.Afterward, the UE 1005 may attempt initial attach at step 1045.

FIG. 11 is a diagram illustrating configurations of EAB informationincluded in SIB14.

Referring to FIG. 11, a cell may be shared several operators. PublicLand Mobile Network (PLMN) denotes a network operated with a networkname. The operators may provide services of a plurality networks withinone cell or share one cell for the operator networks, i.e. PLMNs. Onecell can serve up to 6 PLMNs, and a list of the PLMNs is broadcast inthe SIB1 of the corresponding cell.

In the case that one cell is shared by several operators, there may beMTC devices registered with the operators within the cell. In the casethat traffic load increases in the network of a certain operator, it isnecessary to restrict the access of the MTC devices using thecorresponding operator network selectively. Accordingly, if the EABinformation is provided per PLMN, this may facilitate such control. Anembodiment of the present invention proposes a method of configuringper-PLMN EAB information efficiently.

An EAB set 1100 consists of 10 bits of which each bit indicates whethera specific class is allowed for access. That is, every UE has a classselected in the range of 0 to 9, and the 10-bit information indicateswhether the respective classes are allowed for access. If each bit isset to 0 to indicate access restriction or 1 to indicate accessallowance for the corresponding class. The EAB information may bedifferent from or identical with the ACB information made up of thebarring factor and barring time information as described above. It isalso possible to transmit the per-PLMN barring factors and barring timesaccording to an embodiment.

The number of EAB sets is equal to the number of PLMNs listed in thePLMN list carried in the SIB1. That is, if the PLMN list includes 6PLMNs, total 6 EAB sets exist. It is necessary to map the PLMNs in thePLMN list to the EAB sets as exemplified in such a way of mapping in theorder of arrangement in the present invention. For example, if the PLMNsare contained in the PLMN list of SIB1 like {PLMN 1, PLMN 2, PLMN 3,PLMN 4, PLMN 5, PLMN 6}, the EAB sets 1, 2, 3, 4, and 5 contained inSIB14 may correspond to PLMN 1, PLMN 2, PLMN 3, PLMN 4, PLMN 5, and PLMN6 respectively.

In an embodiment, if the PLMNs of the PLMN list have the same EAB setfor optimization, only one EAB set is carried in SIB14. After receivingboth the SIB1 and SIB14, if the SIB14 includes only one EAB set 1105independently of the number of PLMNs included in the PLMN list of SIB1,the UE may apply the corresponding EAB set to all the PLMNs.

FIG. 12 is a signal flow diagram illustrating a procedure of providingmultiple EABs in the system overload situation.

Referring to FIG. 12, the eNB 1205 may provide the UE 1200 with a listof PLMNs available for service through SIB1 at step 1220. The eNB 1205is shared by the PLMNs A and B. Other PLMNs not shown in the drawingsmay share the eNB 1205 too.

The MME1 1210 belonging to the PLMN A detects a CN overload situation atstep 1225.

The MME1 1210 notifies the eNB 1205 of the CN overload situation andoverload level through an OVERLOAD START message. The overload may bereported using various types of message depending on the embodiment.

The eNB 1205 may configure an EAB for the PLMN A in consideration of theCN overload level and send the EAB to the UE 1200 at step 1235. In thisembodiment, since the PLMN B is not in a CN overload situation, the eNB1205 sends the UE 1200 the EAB for the PLMN B of which every bit is setto 0.

The UE 1205 receives the EAB set and determines whether its access isbarred in consideration of its AC.

The MME2 1215 belonging to the PLMN B detects the CN overload situationat step 1240

The MME2 1215 notifies the eNB of the CN overload situation and overloadlevel through the OVERLOAD START message at step 1245.

The eNB 1205 may configure an EAB for the PLMN B in consideration of theCN overload level and send the EAB to the UE 1200 at step 1250. Sincethe PLMN A is in the CN overload situation yet, the EAB set for the PLMNA is provided together. The UE 1200 receives an EAB set and determineswhether the access is barred in consideration of its AC.

The MME1 1210 belonging to the PLMN A detects that the CN overloadsituation is resolved at step 1225.

The MME1 1210 notifies the eNB 1205 of the resolution of CN overloadsituation through an OVERLOAD STOP message at step 1260. Various typesof message may be used to notify of the overload resolution. Theoverload may be reported using various types of message depending on theembodiment.

The eNB 1205 may configure an EAB set of the PLMN A of which all bitsare set to 0 in consideration of the CN overload level of the PLMN A andtransmits the EAB set to the UE 1200 at step 1265. Since the PLMN B isin the CN overload situation yet, the EAB set for the PLMN B is providedconstantly. The UE 1200 receives the EAB set and determines whether theaccess is barred in consideration of its AC.

The MME2 1215 belonging to the PLMN B detects the CN overload situationis resolved at step 1270.

The MME2 1215 notifies the eNB 1205 of the resolution of CN overloadsituation through the OVERLOAD STOP message at step 1275.

If the CN overload is resolved for all the PLMNs, the eNB 1205determines that it is not necessary to provide EAB any longer at step1280. The UE 1200 may check this situation through SIB update procedureand, if no EAB is received, release the access barring.

FIG. 13 is a flowchart illustrating the eNB operation.

Referring to FIG. 13, the eNB creates SIB1 including the PLMN listlisting n (up to 6) PLMN IDs at step 1300.

The eNB broadcasts the SIB1 for use by the UE at step 1305.

The eNB determines whether the network is in the overload state at step1310.

The eNB includes in the SIB1 the per-PLMN EAB sets in consideration ofthe arranged order of the PLMNs in the PLMN list and the arranged orderof the PLMN-specific EAB sets.

The eNB sets the EAB sets for the PLMNs to which EAB is not applied to 0at step 1320.

The eNB broadcasts the SIB14 for use by the UE at step 1325.

FIG. 14 is a block diagram illustrating a configuration of the UEaccording to an embodiment of the present invention.

Referring to FIG. 14, the UE includes a higher layer device 1410generating data and a control message processor 1415 for processingcontrol message. The UE multiplexes the control signals and data to betransmitted to the eNB by means of the multiplexor/demultiplexer 1405and transmits the multiplexed data by means of the transceiver 1400under the control of the controller 1420. The UE receives a physicalsignal by means of the transceiver 1400, demultiplexes the receivedsignal, and delivers the demultiplexed signal to the higher layer device1410 or the control message processor 1415 under the control of thecontroller 1420.

FIG. 15 is a block diagram illustrating a configuration of the eNBaccording to an embodiment of the present invention.

Referring to FIG. 15, the eNB includes a transceiver 1505, a controller1510, a multiplexer/demultiplexer 1520, a control message processor1535, various higher layer processors 1525 and 1530, and a scheduler1515. The transceiver transmits data and control signals on a downlinkcarrier and receives data and control single on an uplink carrier. Inthe case that a plurality of carriers is configured, the transceiver1505 may transmit and receive data and signals on the plural carriers.The multiplexer/demultiplexer 1520 multiplexes the data generated by thehigher layer processors 1525 and the control message processor 1535 ordemultiplexes the data received by the transceiver 1505 and deliver thedemultiplexed signals to the corresponding higher layer processors 1525and 1530, the control message processor 1535, and/or the controller1510. The control unit 1510 determines whether to include the controlconfiguration information in the control message. The control messageprocessor 1535 generates a control message to be transmitted to the UEand sends the generated message to the higher layer under the control ofthe controller 1510. The higher layer processors 1525 and 1530 may beconfigured per UE per service to process the data generated by the userservice such as FTP and VoIP and transfers the processed data to themultiplexer/demultiplexer 1520 or processes the data from themultiplexer/demultiplexer 1520 and delivers the processed data to theservice applications of the higher layer. The scheduler 1515 allocatestransmission resource to the UE at an appropriate time point and inconsideration of the buffer state, channel state, and active time of theUE and controls the transceiver to process the signal transmitted by theUE or transmit signals to the UE.

It is to be appreciated that those skilled in the art can change ormodify the embodiments without departing the technical concept of thisinvention. Accordingly, it should be understood that above-describedembodiments are essentially for illustrative purpose only but not in anyway for restriction thereto. Thus the scope of the invention should bedetermined by the appended claims and their legal equivalents ratherthan the specification, and various alterations and modifications withinthe definition and scope of the claims are included in the claims.

Although preferred embodiments of the invention have been describedusing specific terms, the specification and drawings are to be regardedin an illustrative rather than a restrictive sense in order to helpunderstand the present invention. It is obvious to those skilled in theart that various modifications and changes can be made thereto withoutdeparting from the broader spirit and scope of the invention.

What is claimed is:
 1. A method performed by a terminal in acommunication system, the method comprising: receiving, from a basestation, a system information block (SIB), wherein the SIB includesinformation on a list of public land mobile networks (PLMNs) for a celland first barring configurations for each of the PLMNs, each of thefirst barring configurations being associated with a plurality of firstbarring factors, wherein each of the first barring factors is appliedfor different access categories corresponding to types of accessattempts; identifying a barring configuration from the first barringconfigurations, the barring configuration corresponding to an accesscategory for a PLMN from the PLMNs; and performing an access barringcheck for the access category based on the barring configuration,wherein each of the first barring configurations corresponds to adifferent PLMN from the PLMNs.
 2. The method of claim 1, wherein the SIBfurther includes second barring configuration for the PLMNs, and whereinthe second barring configuration is common for the PLMNs.
 3. The methodof claim 2, wherein each of the first barring configurations isassociated with a plurality of first barring times, wherein each of thefirst barring times is applied for different access categories, whereinthe second barring configuration is associated with a plurality ofsecond barring factors and a plurality of second barring times, whereineach of the second barring factors is applied for different accesscategories, and wherein each of the second barring times is applied fordifferent access categories.
 4. The method of claim 3, wherein theaccess barring check is performed by using a barring factor and abarring time corresponding to the barring configuration as a barringparameter.
 5. The method of claim 1, wherein each of the access attemptsis for at least one of an emergency call, a mobile originating (MO)call, a voice call, a video call, or a short message service (SMS) call.6. A method performed by a base station in a communication system, themethod comprising: generating a system information block (SIB), whereinthe SIB includes information on a list of public land mobile networks(PLMNs) for a cell and first barring configurations for each of thePLMN, each of the first barring configurations being associated with aplurality of first barring factors, wherein each of the first barringfactors is applied for different access categories corresponding totypes of access attempts; and transmitting, to a terminal, the SIB,wherein a barring configuration corresponding to an access category fora PLMN from the PLMNs is identified from the first barringconfigurations, wherein an access barring check for the access categoryis performed by the terminal based on the barring configuration, andwherein each of the first barring configurations corresponds to adifferent PLMN from the PLMNs.
 7. The method of claim 6, wherein the SIBfurther includes second barring configuration for the PLMNs, and whereinthe second barring configuration is common for the PLMNs.
 8. The methodof claim 7, wherein each of the first barring configurations isassociated with a plurality of first barring times, wherein each of thefirst barring times is applied for different access categories, whereinthe second barring configuration is associated with a plurality ofsecond barring factors and a plurality of second barring times, whereineach of the second barring factors is applied for different accesscategories, and wherein each of the second barring times is applied fordifferent access categories.
 9. The method of claim 8, wherein theaccess barring check is performed by using a barring factor and abarring time corresponding to the barring configuration as a barringparameter.
 10. The method of claim 6, wherein each of the accessattempts is for at least one of an emergency call, a mobile originating(MO) call, a voice call, a video call, or a short message service (SMS)call.
 11. A terminal in a communication system, the terminal comprising:a transceiver; and a controller coupled with the transceiver andconfigured to: receive, from a base station, a system information block(SIB), wherein the SIB includes information on a list of public landmobile networks (PLMNs) for a cell and first barring configurations foreach of the PLMN, each of the first barring configurations beingassociated with a plurality of first barring factors, wherein each ofthe first barring factors is applied for different access categoriescorresponding to types of access attempts, identify a barringconfiguration from the first barring configurations, the barringconfiguration corresponding to an access category for a PLMN from thePLMNs, and perform an access barring check for the access category basedon the barring configuration, wherein each of the first barringconfigurations corresponds to a different PLMN from the PLMNs.
 12. Theterminal of claim 11, wherein the SIB further includes second barringconfiguration for the PLMNs, and wherein the second barringconfiguration is common for the PLMNs.
 13. The terminal of claim 12,wherein each of the first barring configurations is associated with aplurality of first barring times wherein each of the first barring timesis applied for different access categories, wherein the second barringconfiguration is associated with a plurality of second barring factorsand a plurality of second barring times, wherein each of the secondbarring factors is applied for different access categories, and whereineach of the second barring times is applied for different accesscategories.
 14. The terminal of claim 13, wherein the access barringcheck is performed by using a barring factor and a barring timecorresponding to the barring configuration as a barring parameter. 15.The terminal of claim 11, wherein each of the access attempts is for atleast one of an emergency call, a mobile originating (MO) call, a voicecall, a video call, or a short message service (SMS) call.
 16. A basestation in a communication system, the base station comprising: atransceiver; and a controller coupled with the transceiver andconfigured to: generate a system information block (SIB), wherein theSIB includes information on a list of public land mobile networks(PLMNs) for a cell and first barring configurations for each of thePLMN, each of the first barring configurations being associated with aplurality of first barring factors, wherein each of the first barringfactors is applied for different access categories corresponding totypes of access attempts, and transmit, to a terminal, the SIB, whereina barring configuration corresponding to an access category for a PLMNfrom the PLMNs is identified from the first barring configurations,wherein an access barring check for the access category is performedbased on the barring configuration, and wherein each of the firstbarring configurations corresponds to a different PLMN from the PLMNs.17. The base station of claim 16, wherein the SIB further includessecond barring configuration for the PLMNs, and wherein the secondbarring configuration is common for the list of PLMNs.
 18. The basestation of claim 17, wherein each of the first barring configurations isassociated with a plurality of first barring times, and wherein each ofthe first barring times is applied for different access categories,wherein the second barring configuration is associated with a pluralityof second barring factors and a plurality of second barring times,wherein each of the second barring factors is applied for differentaccess categories, and wherein each of the second barring times isapplied for different access categories.
 19. The base station of claim18, wherein the access barring check is performed by using a barringfactor and a barring time corresponding to the barring configuration asa barring parameter.
 20. The base station of claim 16, wherein each ofthe access attempts is for at least one of an emergency call, a mobileoriginating (MO) call, a voice call, a video call, or a short messageservice (SMS) call.